Simulation On Performances Of Solar Air Heating System With Phase Change Materials For Thermal Storage

With the improvement of living standards,people have higher and higher requirements for living environment comfort,and building energy consumption remains high.Using solar energy for building heating is an important means to realize building energy saving.Heat storage technology can solve the problem of uneven solar energy distribution in time.The combination of pebble and phase change material with solar air-heating system can effectively reduce the fluctuation of room temperature,improve the comfort of the room and realize the building energy saving.In this paper,a 16.2m~2 single-storey building room in Beijing area is taken as the simulation object.TRNSYS software is used to establish the pebble bed energy storage and phase change material energy storage solar air heating system.Firstly,the performance of the solar air collector,the average temperature and heat supply of the pebble bed and the temperature variation in the room during the operation of the heating system with energy storage in pebble bed are simulated,and the following results are obtained:When the area of solar air collector is 5m~2,the volume of pebble heat storage bed is 0.7m~3,the pebble mass is 1250kg and the air volume of heating system is 180m~3/h,the total effective heat collection of the collector is 2.4×10~6kJ,the outlet temperature of the collector is mainly between 25℃and 55℃,and the collector efficiency is between 30%and 48%most of the time.The maximum daytime temperature of pebble bed can reach 45℃ on average,and the heat supply of pebble bed is 9.5×10~5 kJ.The room temperature can be maintained at least 10℃ during the whole heating season.Secondly,the performance of heating system with energy storage of phase change material is simulated.The phase change material is paraffin wax with phase change temperature of 22℃.By comparing the phase change material energy storage heating system with the pebble bed energy storage heating system,the conclusion is drawn:Under the condition of the same system parameters and the same heat storage volume,the effect of phase change material energy storage heating system is better than that of pebble bed energy storage heating system.The average room temperature is 2℃ higher,and the indoor temperature fluctuation is small.The total heat supply of phase change module is 3×10~5 kJ more than that of pebble bed.Finally,the influence of collector area,collector flow rate,amount of phase change material and phase change temperature on the solar air heating system with phase change material energy storage was analyzed.For the 16.22 simulated building,the optimal parameter values were:The collector area is 6m~2,the collector unit area flow is 40m~3/(h·m~2),the number of phase change heat storage units is 10,the phase change temperature is 22℃.The collector area and phase change temperature have the greatest influence on the heating effect.Under the above parameters,the simulation results show that the total heat absorbed by the phase change module in the whole heating season is 1.8×10~6kJ,and the lowest temperature of the room can reach more than 13℃.Adding an auxiliary heat source into the system can make the temperature of the room fully meet the heating requirements,that is,in the daytime at 18-22℃,at night at more than 15℃.At this point,the total heat supply of the auxiliary heat source in the whole heating season is 4.5×10~5kJ.